Px Suspension and Component Facts

Question 1

Undesirable effects pistoning creates

Answer 1

1) Generation of shear stresses on skin

2) Functional elongation of the px during swing phase

Question 2

Most effective suspensions to reduce pistoning:

Answer 2

1) Atmospheric Pressure Suspension
2) Anatomic Suspension
3) Strap Suspension
4) Hinge Suspension

Question 3

Preferred suspension whenever feasible

Answer 3

Atmospheric Pressure Suspension

Question 4

Affects from non total contact with atmospheric pressure suspension:

Answer 4

1) Skin damage
2) Capillary breakages
3) Fluid Drainage
4) Thickening and furrowing of skin
5) Malignancy

Question 5

3 Practical limitations from a suction socket:

Answer 5

1) Inability to don or doff the socket consistently
2) Inability to maintain vacuum
3) Inability of the skin to tolerate direct contact with the hard socket walls

Question 6

Developer of the roll-on liner

Answer 6

Ossur Kristinsson of Iceland

Question 7

ICEROSS stands for

Answer 7

Icelandic Roll-On Suction Socket

Question 8

To create an effective vacuum seal how much of rubber must seal against the socket and extend onto the thigh?

Answer 8

2 cm

Question 9

Next best suspension after atmospheric suspension:

Answer 9

Anatomic- advantage of anatomic contours

Question 10

Where is a supracondylar wedge placed?

Answer 10

Area above the medial femoral condyle, just proximal to the adductor muscle

Question 11

Besides suspension, what does the supracondylar wedge add?

Answer 11

Mediolateral control

Question 12

Downfall of strap suspension:

Answer 12

1) Allow significantly pistoning

2) Less comfortable than atmospheric/anatomic suspensions

Question 13

Suprapatellar cuff also known as:

Answer 13

Patellar Tendon Bearing (PTB) Strap

Question 14

Suprapatellar cuff function:

Answer 14

Fit snugly against the suprapatellar tendon during swing phase, suspending the prosthesis over the proximal edge of the patella, and to gradually relax when the knee is flexed beyond 60 degrees so that sitting is comfortable

Question 15

Primary indications today for the use of “joints and lacer” suspension:

Answer 15

Partially unload a fragile residual limb

Question 16

Single-axis Ankle Foot-

Answer 16

increases knee stability

Question 17

Solid Ankle-Cushion Heel Foot-

Answer 17

Popular world wide and has proven to be a very versatile, albeit basic, foot design, and very smooth motion clinically

Question 18

Multi-axial Ankle Foot-

Answer 18

Suites uneven surfaces and absorbs some of the impact of walking

Question 19

Flexible Keel Foot-

Answer 19

Pronation

Supination

Rollover

Makes walking easier

Advised for preparatory px, pediatric px’s, and not recommended aggressive explosive movements

Question 20

Dynamic-Response Foot-

Answer 20

stores potential energy and releases it in the latter part of stance phase

Question 21

Contraindication for dynamic response foot rx:

Answer 21

Amputee is unable or unwilling to load the forefoot, because the spring would be non functional

Question 22

Single Axis Knee-

Answer 22

Pros:

Least expensive

Most maintenance-free

Con:

Has no inherent stability

Rx:

Pediatric application more common

Question 23

Stance Control Knee

Answer 23

Pros:

Most commonly prescribed px knee in the world

Weight activated friction brake

Assists new amputees to learn to walk on a px safely

Appropriate for limited ambulators at a slow pace

Bilateral amputee application is for only one limb

Question 24

Polycentric Knee

Answer 24

Pros:

Stability

Additional toe clearance at swing phase

Help produce a more biomechanically normal gait pattern

Question 25

Manual Lock Knee

Answer 25

Pros:

Provide maximum knee stability

May permit feeble elderly patients to walk more rapidly

Cons:

Functionally too long

Creates abnormal gait deviation

Increases the energy cost of ambulation

Recommendation:

Toddlers and small children for stability

Question 26

Hybrid Knees-

Answer 26

Most popular:

Polycentric combined with hydraulic/pneumatic unit to provide variable cadence swing-phase control

Question 27

Microprocessor Control-

Answer 27

Pros:

Increases gait kinematic control

Increase energy efficiency in gait

Question 28

Torque Absorber

Answer 28

Permits controlled transverse rotation

Absorbs the stresses of the amputees skin

Question 29

Positional Rotator

Answer 29

Allows amputee to passively rotate the lower leg

Use when sufficient space between the knee and socket

Question 30

Shock Absorbing Pylon

Answer 30

Increased comfort when descending stairs, stepping down curves, or getting out of a car

Question 31

Main use for componentry

Answer 31

Match the biomechanical peformance of the components to the individual amputee’s functional goals and physical abilities.